Thanks Loring! This is the tool I didn't know I needed.

[dbhost]

Okay so the router bit vise for working on the bearings on router bits, well... was not something I ever thought I needed, until I did (see my post RE: the Bauer bit set).

Loring kindly sent along one of his surplus router bit vises he made in his shop. This is such a forehead slapping why didn't I think of that kind of basic idea and well executed.

Thank you so much!

Now to see if I can find a replacement bearing, screw is no problem straight forward metric and I have LOTS of those...

[LCHIEN]

You are welcome.

If someone wants to build one, here is the latest design, its pretty easy to build and can be made of scrap wood and about a bucks worth of 1/4-20 hardware
Will save you from slicing your fingers when handling router bits changing/servicing bearings, cleaning or sharpening cutting edges.
The hardware list is 2x 1/4-20 x 2" carriage bolts, 2 x 1/4" washer and 2 x 1/4-20 wing nut. Also 2x 1-1/2" 1/4" dia dowels for the blind holes.

(two downloads)

Original discussion:
https://www.sawdustzone.org/forum/di...outer-bit-vise

[LCHIEN]

In my experience, all my router bit bearings (with SAE fractional dimensions, shanks etc) are either 3/16" ID or 1/4" ID. Even when made abroad. Off hand, I don't know the usual screw thread spec, its a small screw.

I asked AI Gemini and its answer is here - it appears that most Router bits made for the US market are SAE and given the small diameter use #5-40 socket head (3/32") screws for the 3/16" ID bearings and #10-32 screws 5/32" hex socket for the 1/4" ID.
--------------------------------

I have a number of router bits with guide bearings. All are SAE fractional bits, with 1/2" shanks and OD/Length specified in inches. Most of the bearings are 3/16" ID, some are 1/4" ID. Is there a standard screw size retainer for the bearings?




Yes, there are a few highly standardized screw sizes used to retain router bit guide bearings, depending directly on the bearing's inside diameter (ID). [1]
Because your bits are SAE fractional sizes with 1/2" shanks, they almost exclusively use standard Unified National Fine (UNF) socket head cap screws. [1, 2]

Standard Screw Sizes by Bearing ID

• For 3/16" ID Bearings (Most common for tip/edge pilots):
  • Standard Screw Size: #5-40 x 1/4"
  • Hex Key / Wrench Size: 3/32"
  • Note: The #5-40 thread is widely used by major premium brands like Whiteside Machine Company and budget import brands like Uxcell.
• For 1/4" ID Bearings (Common for shank/template pilots):
  • Standard Screw Size: #10-32 x 3/8"
  • Hex Key / Wrench Size: 5/32"
  • Note: Some smaller arbor assemblies or tight-clearance bits may occasionally drop down to a #6-32 or #8-32 screw, but #10-32 is the standard heavy-duty anchor for fractional 1/4" ID configurations. [1, 2, 3, 4]

Important Exceptions to Watch For
If you encounter a bit where the standard sizes listed above do not fit, check for these two brand-specific anomalies:

• Metric Conversions: European brands like CMT Orange Tools or Freud often use metric equivalents. A 3/16" ID pilot might be substituted with an M3 x 0.5mm screw, and a 1/4" ID assembly often uses an M5 screw.
• Left-Hand Threads: On rare specialty bits (like some older arbor-mounted slot cutters), manufacturers use left-handed threads to prevent the rotation of the router from spinning the screw loose. [1, 2, 3]

Quick Verification Tip
Before buying bulk replacement screws, you can easily verify what you have using a standard thread-checker gauge at a local hardware store. Alternatively, you can pick up a dedicated pre-sorted Whiteside Bearing Repair Kit which includes assorted replacement bearings, matching #5-40 screws, and the correct hex keys altogether. [1]
Are you looking to replace stripped screws, or are you planning to swap out the bearings to change your cutting depth profile?

Yes, there is almost always a small washer or specialized shield between the screw head and the bearing.
Its primary purpose is to prevent the screw from locking up the bearing. Without it, the rotating outer ring of the bearing would rub against the stationary screw head, causing friction, heat, and immediate bearing failure.

Types of Washers Used

• Standard Flat Washers: These are tiny, precise washers. The outer diameter (OD) is carefully engineered to only touch the stationary inner race of the bearing, leaving the outer spinning shield completely clear.
• Dust Shields / Cap Washers: Many premium bits use a wider, slightly dished washer. It clamps the inner race firmly but flares out slightly over the face of the bearing without touching it, acting as a physical shield to deflect wood dust and pitch away from the bearing seals.

Critical Caution for Replacements
If you are replacing a lost washer, never use a standard hardware store washer unless you verify its dimensions with calipers.
If the replacement washer is even a fraction of a millimeter too wide, it will bridge the gap between the inner and outer races. The moment you tighten the screw, the bearing will lock up completely, turning your ball-bearing bit into a rubbing pilot that will instantly burn your wood.
If you are missing these washers, they are usually sold in dedicated router bit bearing repair kits alongside the screws to ensure the clearances are exactly right.
Are you missing the washers on all of your bits, or did one specific washer get lost during a cleanup?

[LCHIEN]

you need a washer too.

Yes, there is almost always a small washer or specialized shield between the screw head and the bearing.
Its primary purpose is to prevent the screw from locking up the bearing. Without it, the rotating outer ring of the bearing would rub against the stationary screw head, causing friction, heat, and immediate bearing failure.

Types of Washers Used

• Standard Flat Washers: These are tiny, precise washers. The outer diameter (OD) is carefully engineered to only touch the stationary inner race of the bearing, leaving the outer spinning shield completely clear.
• Dust Shields / Cap Washers: Many premium bits use a wider, slightly dished washer. It clamps the inner race firmly but flares out slightly over the face of the bearing without touching it, acting as a physical shield to deflect wood dust and pitch away from the bearing seals.

Critical Caution for Replacements
If you are replacing a lost washer, never use a standard hardware store washer unless you verify its dimensions with calipers.
If the replacement washer is even a fraction of a millimeter too wide, it will bridge the gap between the inner and outer races. The moment you tighten the screw, the bearing will lock up completely, turning your ball-bearing bit into a rubbing pilot that will instantly burn your wood.
If you are missing these washers, they are usually sold in dedicated router bit bearing repair kits alongside the screws to ensure the clearances are exactly right.
Are you missing the washers on all of your bits, or did one specific washer get lost during a cleanup?

[dbhost]

FWIW, I went ahead and ordered up a Freud bit to replace the Bauer... This bit will be seeing a LOT of heavy use so I figured I might as well get a good one...

[LCHIEN]

yeah, that's probably the better solution. Still I hope the info about bearing and screw sizes is of use for someone. They are largely standardized.

[dbhost]

So the Freud bit arrive and to say it is a LOT sharper than the HF bit is an understatement. Freud did a REALLY good job with this one... I might still end up trying to figure out the diameter of the Bauer bit bearing just because... but